Contactless energy transfer apparatus

ABSTRACT

A flux generator base unit electromagnetically coupled with a receiving unit to transfer energy into the receiving unit. The base unit includes one or more permanent magnets that produce a magnetic flux, which passes through a receiver coil in the receiving unit. The receiver coil is either disposed in a separate housing that is electrically connected with a portable device, or integrated into the housing of the portable device. Either the permanent magnets or a flux shunt is moved in the base unit to produce the varying magnetic flux that is coupled to the receiver coil. As a result of the varying magnetic field experienced by the receiver coil, an electric current is induced in the receiver coil, which is conditioned (e.g., rectified, filtered, and regulated) by a conditioning circuit to charge a battery or energize electronics contained in the portable device. Various embodiments of both the base unit and receiving unit are disclosed, including “universal” base units suitable for operation with different size receiving units.

RELATED APPLICATIONS

[0001] This application is a divisional application, based on priorcopending application Ser. No. 09/547,700, filed Apr. 11, 2000, which inturn is a continuation-in-part of application Ser. No. 09/325,022, filedJun. 3, 1999, which is a divisional application of Ser. No. 09/021,693,filed on Feb. 10, 1998, the benefit of the filing dates of which ishereby claimed under 35 U.S.C. §120.

FIELD OF THE INVENTION

[0002] The present invention generally pertains to contactless transferof electrical energy, and more specifically, to the contactless transferof electromagnetic energy between disparate devices by moving a magnetin one of the devices to vary a magnetic flux experienced by the otherdevice.

BACKGROUND OF THE INVENTION

[0003] Many of today's portable consumer devices, including palm-sizedcomputers, games, flashlights, shavers, radios, CD players, phones,power tools, small appliances, tooth brushes, etc., are powered byrechargeable batteries. The batteries in these devices, which aretypically of the nickel-cadmium, lead-acid, nickel-metal-hydride, orlithium-ion type, must be recharged periodically to enable the continueduse of the devices.

[0004] There are several methods used in the prior art to recharge suchbatteries. For example, many manufacturers produce rechargeablebatteries corresponding to conventional AAA, AA, A, B, C, and D sizes,which are typically recharged using a charger station that is adapted tocharge a certain size battery or a plurality of different sizebatteries. In addition, many power tool manufacturers produce lines ofportable tools energized by batteries that are not of the standard sizeslisted above, but which often share a common form factor and voltagerating. These batteries are typically recharged by removing the batteryfrom the tool and charging it in a specially-adapted charger specific tothat manufacturer's line of tools and specifically designed to rechargebatteries of that voltage. In order to recharge both conventional-sizebatteries and the more specialized portable power tool batteries, it isgenerally necessary to remove the batteries from the portable device andattach them to their respective chargers, and after they are recharged,the batteries must be reinstalled in the portable device. This task isunduly burdensome and time-consuming for the user.

[0005] In order to avoid the burden associated with the foregoing task,some portable consumer devices include a charge-conditioning circuit(either internally or externally) that can be used with a conventionalpower source, such as a wall outlet, to provide a conditioned directcurrent (DC) at a voltage suitable for recharging a battery contained inthe device. For example, it is common for electric shavers to include acharge-conditioning circuit that enables a nickel-cadmium (or othertype) battery retained in the shaver to be recharged by plugging theshaver into a line voltage outlet. Similarly, some flashlights have anintegrated connector that allows them to be recharged by simply pluggingthem into a wall outlet. In addition, certain devices such as portablehand vacuum cleaners use a “base” charger unit for both storing thedevice between uses and recharging the battery. When the portable deviceis stored in the base unit, exposed terminals on the device areconnected through contacts on the base unit to a power supply energizedwith line current, thereby providing a conditioned DC current to chargethe battery within the portable device.

[0006] In all of the foregoing examples, as is true of the majority ofdevices that use rechargeable batteries, some sort of interfacecomprising an electrical connection (i.e., contact) is used to providean appropriate DC voltage for recharging the batteries. However, the useof contacts to connect a battery to a recharging current is undesirable,as they are susceptible to breakage, corrosion, and may present apotential safety problem if used improperly or inadvertently shorted.The shape and configuration of these contacts are also generally uniqueto individual devices, or a manufacturer's product line, making itimpractical to provide a “universal” charging interface that includescontacts.

[0007] Recognizing the problems with recharging batteries with currentsupplied through electrical contacts, several manufacturers now offer“contactless” battery-charging devices. These charging devices aregenerally of two types—inductive charging systems, and infrared chargingsystems. Inductive charging systems include an electromagnetic or radiofrequency coil that generates an electromagnetic field, which is coupledto a receiver coil within the device that includes a battery requiringrecharging. For use in recharging a battery in a handheld poweredtoothbrush, a relatively high-frequency current is supplied to thetransmitter coil in a base for the handheld toothbrush, therebygenerating a varying magnetic field at a corresponding frequency. Thismagnetic field is inductively coupled to a receiver coil in thetoothbrush housing to generate a battery charging current. Anotherexample of such a system is the IBC-131 contactless inductive chargingsystem by TDK Corporation, which switches a nominal 141 volt, 20 mA(max) input current to a transmitter coil at 125 kHz to produce a 5 voltDC output at 130 mA in a receiver coil.

[0008] A different contactless system for charging batteries is aninfrared charging system employing a light source as a transmitter and aphotocell as a receiver. Energy is transferred from the source to thereceiving photocell via light rather than through a magnetic field.

[0009] Both inductive and infrared charging systems have drawbacks.Notably, each system is characterized by relatively high-energy losses,resulting in low efficiencies and the generation of excessive heat,which may pose an undesirable safety hazard. Additionally, thetransmitter and receiver of an inductive charging system generally mustbe placed in close proximity to one another. In the above-referenced TDKsystem, the maximum gap between the receiver and transmitter is 4 mm.Furthermore, in an infrared system, the light source and/or photocellare typically protected by a translucent material, such as a clearplastic. Such protection is typically required if an infrared chargingsystem is used in a portable device, and may potentially affect theaesthetics, functionality, and/or durability of the device.

[0010] It would therefore be desirable to provide a contactless energytransfer apparatus suitable for use with portable consumer devices thatallows a greater spacing between the transmitter and receiver elements,and provides improved efficiency over the prior art. Furthermore, it ispreferable that such an apparatus provide a contactless “universal”interface for use with a variety of different types and/or differentsizes of devices made by various manufacturers.

SUMMARY OF THE INVENTION

[0011] In accord with the present invention, an energy transferapparatus is defined that is adapted for magnetically exciting areceiver coil that includes a core of a magnetically permeable material,by causing an electrical current to flow in the receiver coil. Theenergy transfer apparatus includes a magnetic field generator that isenclosed in a housing and includes at least one permanent magnet. Thehousing is adapted to be disposed proximate another housing in which thereceiver coil is disposed. A prime mover is drivingly coupled to themagnetic field generator to cause an element of the magnetic fieldgenerator to move relative to its housing. Movement of the elementproduces a varying magnetic field that couples with the core of thereceiver coil and induces an electrical current to flow in the receivercoil.

[0012] The prime mover of the energy transfer. apparatus preferablycomprises an electric motor, but can include other types of devicescapable of moving the element. For example, a hand crank can be employedfor moving the element. In one form of the invention, the prime mover isdisposed within the housing in which the magnetic field generator isenclosed. Alternatively, the prime mover is disposed remote from themagnetic field generator and is coupled to the magnetic field generatorthrough a drive shaft.

[0013] In several embodiments of the invention, the prime mover movesthe permanent magnet relative to the receiver coil. Movement of thepermanent magnet varies a magnetic flux along a path that includes thereceiver coil. Increasing a speed at which the permanent magnet is movedincreases a magnitude of the electrical current induced in the receivercoil.

[0014] In one embodiment, the permanent magnet is reciprocated back andforth relative to the receiver coil. The reciprocating movement of thepermanent magnet varies a magnetic flux along a path that includes thereceiver coil.

[0015] A flux linkage bar formed of a magnetically permeable material ispreferably disposed adjacent a magnetic pole of the permanent magnet.The flux linkage bar enhances the coupling of magnetic flux from a poleof the permanent magnet into a path that includes the receiver coil.

[0016] In several embodiments, the magnetic field generator preferablycomprises a plurality of permanent magnets. An adjustment member isincluded to selectively vary a maximum magnetic flux produced by themagnetic field generator for coupling with the receiver coil. A speedcontrol is used as the adjustment member in one embodiment.

[0017] In another embodiment, the permanent magnets include a “driven”permanent magnet that is moved by the prime mover, and a “follower”permanent magnet that is magnetically coupled to the driven permanentmagnet and is moved by its motion.

[0018] In yet another embodiment, the permanent magnets are fixedrelative to the housing, and the moving element comprises a flux shuntthat is moved by the prime mover to intermittently pass adjacent to polefaces of the plurality of permanent magnets so as to intermittentlyprovide a magnetic flux linkage path between the pole faces thateffectively shunts the magnetic flux. When the magnetic flux is thusshunted, substantially much less magnetic flux couples to the receivercoil. The shunting of the magnetic flux through the moving elementeffectively periodically “shuts off” the magnetic field produced by thepermanent magnets that would otherwise be experienced by the receivingcoil, producing the varying magnetic field.

[0019] A further technique for adjusting the maximum magnetic fieldemploys a plurality of turns of a conductor that are wound around eachthe plurality of permanent magnets. The plurality of turns of theconductor are connected to a source of an electrical current, producinga magnetic field that either opposes or aids the magnetic field producedby the permanent magnets, thereby varying the maximum magnetic fieldexperienced by the receiver coil.

[0020] In yet another embodiment, the permanent magnets are radiallymovable relative to an axis of a drive shaft that is rotatably driven bythe prime mover. The permanent magnets are attracted to each other whenthe shaft is at rest, but an actuator moves the permanent magnets awayfrom each other to improve the coupling of the magnetic flux with thereceiver coil when the shaft is rotating. The disposition of thepermanent magnets adjacent to each other when the shaft begins to rotatereduces the startup torque required to rotate the shaft. Furthermore, bycontrolling the radial disposition of the permanent magnets, a magnitudeof the electrical current induced in the receiver coil is selectivelycontrolled.

[0021] According to further aspects of the invention, a contactlessbattery charger/energy transfer apparatus is defined that use theforegoing energy transfer scheme in combination with a conditioningcircuit to recharge a rechargeable storage battery disposed in aportable device. Additionally, the energy can be supplied to electroniccomponents in the portable device. The contactless batterycharger/energy transfer apparatus typically includes a flux generatorbase unit, and a receiver unit. The flux generator is housed in the fluxgenerator base unit, which in several embodiments preferably includes a“universal” mounting provision that enables the base unit to be usedwith receiver units of different sizes. The receiver unit comprises areceiver coil disposed in a housing adapted to mate with the base unit,and a conditioning circuit that conditions the current generated by theenergy inductively coupled into the receiver coil to control thecharging of a battery (or batteries) and/or provide a conditionedcurrent to the electronic components in the portable device. Thereceiver coil housing may be integral to the portable device in whichthe receiver coil is disposed, or it may be a separate component that issuitable for attachment to a variety of different devices.

[0022] In one preferred embodiment, the flux generator base unit andreceiver units are shaped in the form of tablets. The contactlessbattery charger/energy transfer apparatus embodiments additionallyprovide a sensor and an indicator for detecting and indicating when thereceiver unit is mated and properly aligned with the flux generator baseunit. The sensor signal controls the operation of the motor. Theconditioning circuit also includes a detection circuit for determiningwhen a battery is fully charged, and controls the charge currentsupplied to the battery as a function of its charge state. Also includedin the flux generator base unit is a detection circuit for determiningwhen the battery is charged, so that the motor is then turnedde-energized.

[0023] According to another aspect of the invention, a wirelesscommunication channel is effected between the receiver unit and the fluxgenerator base unit by pulsing a load applied to the output of theconditioning circuit, thereby producing a corresponding pulse change inthe current supplied to the electric motor. The pulsing current drawn bythe electric motor is detected to recover the data transmitted from thereceiver unit.

[0024] Another aspect of the present invention is directed to a methodfor charging a battery via a varying magnetic field that is inductivelycoupled to transfer energy to a receiver coil. The steps of this methodare generally consistent with the functions provided by the elements ofthe apparatus discussed above.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0025] The foregoing aspects and many of the attendant advantages ofthis invention will become more readily appreciated as the same becomesbetter understood by reference to the following detailed description,when taken in conjunction with the accompanying drawings, wherein:

[0026]FIG. 1 is a block diagram illustrating the primary components ofthe present invention;

[0027]FIG. 2 is a cross-sectional view of a first embodiment of a fluxgenerator base for coupling a varying electromagnetic flux into areceiver coil in a receiving unit, in accord with the present invention;

[0028]FIGS. 3A and 3B respectively illustrate a cross-sectionalelevational view and a bottom view of a second embodiment of a fluxgenerator base that includes two sets of permanent magnets;

[0029]FIG. 3C is an isometric bottom view of a driven disk for the fluxgenerator, for use as a test prototype;

[0030] FIGS. 3D and 3D′ are respectively a bottom view of the drivendisk, with two permanent magnets, and a graph of related magnetic fieldintensity waveforms vs. time;

[0031] FIGS. 3E and 3E′ are respectively a bottom view of the drivendisk, with four permanent magnets, and a graph of related magnetic fieldintensity waveforms vs. time;

[0032] FIGS. 3F and 3F′ are respectively a bottom view of the drivendisk, with six alternating pole permanent magnets, and a graph ofrelated magnetic field intensity waveforms vs. time;

[0033] FIGS. 3G and 3G′ are respectively a bottom view of the drivendisk, with six permanent magnets in an arrangement with threeconsecutive south pole faces and three consecutive north pole faces onthe bottom of the drive disk, and a graph of related magnetic fieldintensity waveforms vs. time;

[0034] FIGS. 3H and 3H′ are respectively a bottom view of a driven diskincluding a pair of arcuate-shaped permanent magnets, and a graph ofrelated magnetic field intensity waveforms vs. time;

[0035]FIGS. 4A and 4B are respectively a side elevationalcross-sectional view of another embodiment of a flux generator basecoupled to a receiver coil in which a rotating permanent magnet producesa magnetic flux that is coupled to the receiver coil by two flux linkagebars, and a cross-sectional view of the flux generator base taken alongsection lines 4B-4B in FIG. 4A;

[0036]FIG. 5 is a cross-sectional side elevational view of anotherembodiment of the flux generator base and the receiver coil, in which adrive wheel rotates two permanent magnets;

[0037]FIGS. 6A and 6B are respectively a cross-sectional view of yetanother embodiment of the flux generator base and the receiver coil inwhich one permanent magnet is directly driven to rotate and anotherpermanent magnet magnetically follows the rotation of the drivenpermanent magnet, and an enlarged view of the following permanentmagnet;

[0038]FIG. 7 is a plan view of a flux generator base (housing not shown)in which two permanent magnets are driven to reciprocate back and forthabove the receiver coil;

[0039]FIG. 8 is a side elevational view of a flux generator base (only aportion of the housing shown) in which three permanent magnets aredriven to linearly reciprocate below the receiver coil;

[0040]FIG. 9 is a side elevational view of a flux generator base (only aportion of the housing shown) in which conductors coiled around twopermanent magnets selectively vary a magnetic field produced by thepermanent magnets;

[0041]FIG. 10 is a side elevational view of a flux generator base (onlya portion of the housing shown) in which two rotating flux linkage tabsvary the magnetic flux linked between two fixed permanent magnets to thereceiver coil;

[0042]FIGS. 11 and 11′ are respectively an isometric view of a fluxgenerator base (housing not shown) in which fixed permanent magnets anda rotating flux shunt bar are provided, and a graph of the currentpulses vs. time produced in the receiver coil;

[0043]FIG. 12 is a side elevational view of the receiver coil and a fluxgenerator base (only a portion of the housing shown) in which twopermanent magnets are slidably supported within a rotating tube so as tominimize starting torque, and so as to reduce an external magnetic field(outside the housing) when the permanent magnets are not rotating;

[0044]FIGS. 13A and 13B are external power heads in which a force isapplied by a solenoid coil/ring magnet, and by a fluid cylinder,respectively, to two permanent magnets that are slidably mounted in arotating tube so as to minimize starting torque, and so as to reduce anexternal magnetic field (outside the housing) when the permanent magnetsare not rotating;

[0045]FIG. 14 is a cut-away side elevational view of yet another fluxgenerator base including a speed control and a permanent magnet that isdrivingly rotated within a plane, which is generally transverse to theplane of an internal air core receiver coil disposed within the portableapparatus to be charged;

[0046]FIGS. 15A and 15B are respectively an elevational view and planview of a universal charger base implementation of the presentinvention;

[0047]FIG. 16 shows an optional embodiment of the universal charger baseof FIGS. 15A and 15B wherein a pair of flux-generating bars are moved ina linear motion;

[0048]FIG. 17 shows an alternative embodiment of the universal chargerbase of FIGS. 15A and 15B wherein a pair of flux-generating bars aremoved in an elliptical motion;

[0049]FIGS. 18A and 18B are respectively a plan view and a cut-away sideelevational view of a universal charger base that provides a steppedmounting interface for use with various-sized receiver units; and

[0050]FIGS. 19A and 19B are respectively a plan view and a cut-away sideelevational view of yet another alternative embodiment of a universalcharger base that provides a stepped mounting interface for use withvarious-sized receiver units.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0051] With reference to FIG. 1, a block diagram shown thereinillustrates a typical application of the present invention. In thisapplication, a flux generator base 20 includes a local (or remote) motordrive 22 that is energized from a power supply/control 24. Local (orremote) motor drive 22 comprises a prime mover that supplies amechanical driving force to actuate a varying magnetic field generator26. While the motor drive is preferably electrical, it is alsocontemplated that a pneumatic or hydraulic motor can alternatively beused as the prime mover. A pressurized pneumatic or hydraulic fluidsupply and control 24′ is shown for use in controlling such a motor. Byusing a fluid drive motor, electrical current to and in the device iseliminated, which may be desirable in certain applications. However, anelectrically powered motor is typically lower in cost and generallypreferable. To provide electrical current to operate an electricalmotor, power supply/control 24 is preferably energized by connection toan AC line source (not separately shown). However, a DC battery supplymight be used in certain applications, for example, when power isprovided by connection to an automotive electrical system. It is alsocontemplated that a hand crank (not shown) can be employed for actuatingvarying magnetic field generator 26.

[0052] If the mechanical driving force for actuating varying magneticfield generator 26 is provided locally, the motor drive is coupled tothe varying magnetic field generator through a drive shaft 36.Conversely, if the motor drive is disposed at a remote point, separatefrom the varying magnetic field generator, the mechanical driving forcecan be provided through a flexible cable (not separately shown) thatextends between the remote motor drive and varying magnetic fieldgenerator 26. The movement produced by the motor drive causes avariation in the magnetic field produced by magnetic field generatorthat changes the magnetic flux through a path outside of flux generatorbase 20.

[0053] Flux generator base 20 is intended to produce a varying magneticfield that induces a corresponding electrical current to flow in aconductor. The conductor is disposed sufficiently close to the fluxgenerator base to enable magnetic coupling between the conductor and theflux generator to occur. In one preferred application of the fluxgenerator base, the varying magnetic field it produces passes through ahousing 28 in which the varying magnetic field generator is disposed anda separate housing 29 in which the rechargeable battery is stored, andcouples with a receiver coil 30 that is positioned inside housing 29,directly opposite varying magnetic field generator 26. Preferable,housings 28 and 29 comprise material through which magnetic flux readilypasses, such as a plastic, fiberglass, or a composite. A typicalseparation between varying magnetic field generator 26 and receiver coil30 is from about 0.5 cm to about 2.0 cm.

[0054] Receiver coil 30 is connected to a conditioning circuit 34through a lead 32, which conveys the electrical current induced in thereceiver coil by the varying magnetic field; this electrical current isthen appropriately regulated by the conditioning circuit to achieve avoltage and current appropriate to recharge the battery (or batteries)connected thereto.

[0055] The conditioning circuit may be used to energize a storagebattery or storage capacitor for storing energy coupled to receiver coil30. Alternatively, a battery or capacitor for storing energy (neithershown) may be disposed at the receiver coil. It will also be apparentthat the portable apparatus can be directly energized using the presentinvention, in which case, an energy storage device need not be provided.

[0056]FIG. 2 illustrates a first embodiment of flux generator base 20 inwhich motor drive 22 is disposed within housing 28 of the flux generatorbase. Motor drive 22 is coupled to a generally elongated U-shapedpermanent magnet 42 through rotating drive shaft 36. The rotating driveshaft connects to a collar 44 around the midsection of permanent magnet42. Preferably in this and in each of the other embodiments of thepresent invention described below, the permanent magnet is formed of aneodymium-iron-boron alloy or other rare earth or metal alloy thatproduces a relatively high magnetic flux density. Other types offerro-magnetic alloys are also acceptable for this purpose, although itis generally desirable to use a material for the permanent magnets thatproduces a relatively strong magnetic field in the present invention.Permanent magnet 42 includes a north pole face 46 and a south pole face48 that face upwardly and are disposed immediately adjacent the interiorside of the lower surface of housing 28 (as depicted in the Figure—itwill be noted that only the relative orientation of the components isimportant, not their absolute orientation). To prevent undesiredshunting of the magnetic flux between north pole face 46 and south poleface 48 and eddy current losses that would occur if a conductivematerial were used, housing 28 preferably comprises a plastic polymermaterial that is a good electrical insulator and does not block themagnetic flux produced by the permanent magnet. In instances where themotor drive comprises an electric motor, an electrical currentappropriate to energize the motor drive is supplied by electrical leads52, which run through a grommet 54 disposed in the side of housing 28.

[0057]FIGS. 3A and 3B show an alternative embodiment, illustrating avarying magnetic field generator 60. In these Figures, the housing andmotor drive of the charger are not illustrated, but it will be apparentthat a housing such as housing 28 can enclose varying magnetic fieldgenerator 60. A local or a remote motor drive is coupled to a driveshaft 64 to rotate a disk 62, which comprises the varying magnetic fieldgenerator, in either direction about a longitudinal axis of drive shaft64. Embedded within disk 62 are two sets of permanent magnets 66 and 68;the north pole face of one of these permanent magnets and the south poleface of the other permanent magnets are generally flush with the lowersurface of disk 62 (as shown in the Figure). A flux linkage bar 70extends between the south and north pole faces of permanent magnets 66(within disk 62), while a flux linkage bar 72 extends between the northand the south pole faces of permanent magnets 68 (within disk 62). Therelationship of the permanent magnets and flux linkage bars are bestillustrated in FIG. 3B.

[0058] Rotation of disk 62 about its central axis in either directionvaries the magnetic field experienced at receiver coil 30 (shown inFIG. 1) and alternately changes the polarity of the field as thedifferent permanent magnets rotate to positions adjacent to the polefaces of the receiver coil. The varying magnetic field that is thusproduced by rotation of disk 62 induces a generally correspondingvarying electrical current in the receiver coil that is usable toenergize a device such as a portable hand tool. Preferably, theelectrical current supplied to the device is first conditioned byconditioning circuit 34 (also shown in FIG. 1), for example, to rectify,filter, regulate the current. The speed at which disk 62 rotates changesthe frequency of the induced electrical current and also varies theaverage magnitude of the electrical current induced in the receivercoil. It is contemplated that disk 62 can be rotated at a rate such thatthe frequency of the current induced in the receiver coil is within therange from less than 10 Hz to more than 10 kHz.

[0059] It should be noted that the power transferred to the receivercoil increases as the rotational speed of the varying magnetic fieldgenerator increases. Also, as the relative spacing between varyingmagnetic field generator 60 and the receiver coil changes, the amplitudeof the induced electrical current also changes, i.e., the magnitude ofthe induced electrical current increases as the separation decreases.While not shown in any of the Figures, it will be apparent that theelevation of rotating disk 62 above the receiver coil can be readilychanged to modify the respective separation between the two devices andthereby selectively determine the maximum current induced in thereceiver coil— all other parameters such as rotational speed remainingconstant.

[0060] FIGS. 3D-3G show further embodiments of the varying magneticfield generator of the type illustrated in FIGS. 3A and 3B. The diskconfiguration for the varying magnetic field generator illustrated inthese Figures was first used to confirm the effectiveness of the presentinvention. In FIG. 3C, a disk 62′ is shown without any permanentmagnets. In an embodiment 60′ shown in FIG. 3D, only two permanentmagnets 75 and 76 are inserted within disk 62′, and other cavities 74 indisk 62′ do not contain permanent magnets. As shown in the Figure,permanent magnet 75 is positioned within disk 62′ with its north poleface facing downwardly, flush with the lower surface of the disk, whilepermanent magnet 76 is positioned with its south face facing downwardly,flush with the lower surface of the disk. The opposite pole faces ofeach of permanent magnets 75 and 76 are directed upwardly, and thelongitudinal axes of the permanent magnets are generally alignedparallel with the axis of drive shaft 64.

[0061] To test the efficacy of the embodiments shown in FIGS. 3D-3G,drive shaft 64 was simply chucked in a drill press (not shown) androtated so that the lower surface of the disk in which the permanentmagnets are embedded passed immediately above a receiver coil (generallylike receiver coil 132—shown in FIG. 2). Using only one permanent magnet75 and one permanent magnet 76 as shown in FIG. 3D, the magnetic fieldintensity waveforms illustrated in the graph of FIG. 3D′ were produced,which include positive pulses 78 and negative pulses 80.

[0062] When two permanent magnets 75 and two permanent magnets 76 weredisposed opposite each other as shown in FIG. 3E, rotation of a disk 62′induced magnetic field intensity waveforms comprising two positivepulses 82 followed by two negative pulses 84 in repetitive sequence, asshown in FIG. 3E′. Alternating permanent magnets 75 and 76 in each ofthe cavities formed in a disk 62′″ to produce a varying magnetic fluxgenerator 60′″ as shown in FIG. 3F, produced higher frequency magneticfield intensity waveforms, including positive pulses 86 and negativepulses 85, which are more sinusoidal, as indicated in FIG. 3F″″. In theembodiment of varying magnetic field generator 60″, shown in FIG. 3G,three permanent magnets 75 are disposed adjacent each other with theirnorth pole faces flush with the lower surface of a disk 62″″, whilethree permanent magnets 76 have the south pole face flush with the lowersurface of the disk. Rotation of disk 62″″ produced the magnetic fieldintensity waveforms shown in FIG. 3G′, which include three positivepulses 88 followed by three negative pulses 90, in repetitive fashion.

[0063] In FIG. 3H, a disk 87 includes two generally arcuate-shapedpermanent magnets 89 and 91 disposed adjacent radially opposite sides ofthe disk, with the north pole of permanent magnet 89 and the south poleof permanent magnet 91 flush with the lower surface of the disk (asshown in the Figure). A flux linkage bar 93 extends across the disk,over the opposite poles of the two permanent magnets. Due to the arcuateshape of the permanent magnets, they extend over a larger portion of therotational arc of disk 87, causing generally sinusoidal magnetic fieldintensity waveforms 95 and 99 to be magnetically induced in the receivercoil, as shown in FIG. 3H′.

[0064] At relatively slow rotational speeds, the rotation of one or morevery strong permanent magnets directly below a receiver coil may applysufficient torque to the receiver coil to cause the receiver coil tomove back and forth slightly. However, any movement or vibration of thereceiver coil due to such torque will be substantially eliminated whenthe receiver coil is attached to the device that is to be energized orwhich includes a battery to be charged by the present invention.Furthermore, if the rotational speed of the varying magnetic fieldgenerator is sufficiently high, the effects of any torque applied to thereceiver coil will be almost imperceptible.

[0065] In FIGS. 4A and 4B, a flux generator base 92 is illustrated thateliminates virtually all torque on the receiver coil. In thisembodiment, a permanent magnet 94 is coupled through a connection 102 toa flexible cable 100, which turns within a flexible drive shaft 97.Flexible cable 100 is connected to a remote electrical drive motor (notshown in this Figure) that applies a rotational driving force to theflexible drive shaft. The flexible drive shaft rotates within a bearing96 that is supported in a cylindrical-shaped housing 104 of fluxgenerator base 92. Cylindrical-shaped housing 104 preferably isfabricated of a plastic polymer that does not block or shunt magneticflux and which does not conduct eddy currents. Inside cylindrical-shapedhousing 104, at diametrically opposite sides of the housing, aredisposed two vertically aligned flux linkage blocks 98. As permanentmagnet 94 rotates, its north and south poles pass adjacent to the topinwardly facing surfaces of flux linkage blocks 98, as shown clearly inFIG. 4B. The magnetic flux produced by permanent magnet 94 is conveyedthrough the flux linkage blocks and coupled into an overlying receivercoil 132. Flux generator base 92 is disposed relative to receiver coil132 such that the upper ends of the flux linkage blocks are disposedopposite core faces 136 of the receiver coil. Since permanent magnet 94rotates in a plane that is substantially spaced apart from the top ofcylindrical-shaped housing 104 (as illustrated in the Figure), thepermanent magnet applies substantially less attraction to the overlyingreceiver coil than would be the case if the permanent magnet wererotating in a plane closer to the receiver, e.g., immediately adjacentto the top of the cylindrical-shaped housing. Furthermore, flux linkageblocks 98 tend to concentrate the magnetic flux produced by the rotatingpermanent magnet in a vertical direction, minimizing any horizontalcomponent of the magnetic flux, so that little rotational force isexperienced by adjacent core faces 136 of receiver coil 132.

[0066] Referring now to FIG. 5, another embodiment comprising a fluxgenerator base 110 is disclosed. In flux generator base 110, twocylindrical permanent magnets 124 are provided, each of which rotatearound shafts 130 that extend through their respective centers.Alternatively, more conventional bar-shaped permanent magnets mounted ina plastic polymer cylinder can be used. Mechanical link bars 118 areattached to each of the permanent magnets at pivot points 122 and extendto a common pivot point 120 on a rotating driven wheel 114 that isdisposed midway between the two permanent magnets. Driven wheel 114 isrotated by a drive shaft 116 that is connected to an electrical drivemotor (not shown) disposed either within flux generator base 110, oralternatively, at a more remote location, as discussed above. Sincepivot point 120 is offset from drive shaft 116, i.e., offset from thecenter of the driven wheel 114, movement of pivot point 120 due torotation of the driven wheel is translated by mechanical link bars 118into a corresponding rotational force applied to pivot points 122 thatcauses permanent magnets 124 to rotate about their shafts 130. Ascorresponding north and south poles on permanent magnets 124 move topositions immediately adjacent a curved flux linkage bar 126, theopposite poles of the permanent magnets are disposed adjacent verticallyaligned flux linkage bars 128. In this Figure, the lower ends of theflux linkage bars are disposed adjacent the top of flux generator base110, spaced apart and directly opposite core faces 136 of a core 134comprising receiver coil 132. This core is fabricated of a metal oralloy having a relatively high magnetic permeability. Coiled about core134 are a plurality of turns 138 of an electrical conductor, the ends ofwhich comprise a lead 140, which extends to the conditioning circuit(not shown in this Figure) that rectifies, filters, and regulates thecurrent from receiver coil 132, as required by the device in which thereceiver coil is installed. The varying magnetic flux applied toreceiver coil 132 induces a corresponding varying electrical current toflow through turns 138 and through lead 140.

[0067] Another embodiment of a flux generator base 150 is illustrated inFIG. 6A. In this embodiment, a driven wheel 152, fabricated of a plasticpolymer or other suitable non-magnetic material bonded to a pair ofpermanent magnets 154, is rotated by a motor drive 162. Magnetic fluxfrom permanent magnets 154 is coupled through a horizontally extendingflux linkage bar 158 disposed below the driven wheel (as shown in theFigure) to a follower wheel 156, which also includes a pair of permanentmagnets 154 bonded together with their respective north and south polefaces facing each other, separated by a flux linking section 157, bestseen in FIG. 6B. (The structure of driven wheel 152 is substantiallyidentical to that of follower wheel 156.) Rotation of driven wheel 152causes a varying magnetic field polarity to be experienced by permanentmagnets 154 on follower wheel 156 and the interaction with this magneticfield rotates the follower wheel generally in lock step with therotation of driven wheel 152. As a consequence, magnetic flux from thepairs of permanent magnets 154 on the driven wheel and follower wheelcouple into receiver coil 132, inducing an electrical current to flow inturns 138 for use in energizing a portable device or charging itsbatteries.

[0068] The embodiments of flux generator bases discussed thus far haveall included permanent magnets that rotate. In FIG. 7, a flux generatorbase 170 is illustrated that includes a flux linkage bar 174 mounted toa shaft 176. Shaft 176 reciprocatively rotates back and forth, causingpermanent magnets 172 to pass back and forth above core faces 136 ofreceiver coil 132. As the magnetic flux produced by the permanentmagnets and experienced by receiver coil 132 periodically changes due tothe reciprocating movement of the permanent magnets back and forth belowthe pole faces of the receiver coil, an electrical current is induced toflow within the turns of the conductor (not shown in FIG. 7) wrappedaround core 134. This electrical current is typically rectified,filtered, and regulated to meet the requirements of the device coupledto the receiver coil.

[0069] Instead of being rotatably reciprocated back and forth, thepermanent magnets can be driven to move back and forth in a linearfashion, as in the embodiment of a flux generator base 180 illustratedin FIG. 8. In this embodiment, a flux shunt bar 186 is disposed belowthree vertically-aligned and spaced-apart permanent magnets 182 andextends over the respective north and south poles of two of thepermanent magnets. The downwardly facing poles of permanent magnets 182are respectively south, north, and south (or each can be of oppositepolarity), in the order in which they are attached to a moving plate 184that is reciprocatively driven back and forth. The spacing betweenpermanent magnets 182 is such that at the two extreme linear positionsof reciprocating plate 184, the poles of two of the permanent magnetsare disposed immediately below core faces 136 on receiver coil132;,these poles are opposite in polarity. Linear reciprocating movementof reciprocating plate 184 is provided by an appropriate drive mechanism(not shown), receiving its motive power from an electrical motor drive(also not shown), which is disposed either locally with the fluxgenerator base, or remotely and coupled to the flux generator base by adrive shaft.

[0070] In FIG. 9, an embodiment of a flux generator base 190 isillustrated that includes provision for selectively electricallycontrolling the strength of the magnetic field coupled to receiver coil132. In this embodiment, instead of varying the separation betweenrotating permanent magnets 192 and receiver coil 132, an electricalconductor 194 is coiled around each of permanent magnets 192 and iscoupled to a variable current power supply (not shown) that provides adirect current (DC) flowing through conductor 194. Note that permanentmagnets 192 can be rotated about a common axis that is orthogonal to theaxes of the rotation shown in the Figure. Since permanent magnets 192are rotating, being driven by an electrical motor drive (also not shownin FIG. 9), conductor 194 must be coupled to the variable power supplyusing slip rings, brushes, a rotary transformer, or other suitablemechanism, as is commonly used for coupling power to a conductor on arotating armature of an electric motor. The DC current passing throughconductor 194 can either assist or oppose the magnetic field produced bypermanent magnets 192, thereby selectively varying the strength of themagnetic field experienced by receiver coil 132 to control the magnitudeof the electrical current that the receiver coil supplies to theconditioning circuit.

[0071] Another way to periodically vary the magnetic field experiencedby receiver coil 132 is to periodically change the efficiency with whichthe magnetic flux produced by permanent magnets couples to the receivercoil. FIG. 10 illustrates one technique for varying the magnetic fluxlinkage between two permanent magnets 202 in a flux generator base 200and the receiver coil. Permanent magnets 202 are stationary. A motordrive (not shown in this Figure) drivingly rotates two disks 204 thatare disposed behind each of the fixed permanent magnets. Tabs 206 extendoutwardly from the facing surfaces of disks 204 a distance equal to alittle more than the thickness of permanent magnets 202 (measured in adirection normal to the plane of the paper in the Figure). Tabs 206 anddisks 204 are fabricated of a metal or an alloy having a high magneticpermeability that provides enhanced flux linkage when disposed adjacentthe poles of permanent magnets 202. A flux shunt bar 186 that is alsofabricated of a material having a high magnetic permeability extendsbelow permanent magnets 202 (as shown in this Figure), but is spacedsufficiently apart from the downwardly facing poles of the permanentmagnets to provide clearance for tabs 206 to pass between the flux shuntbar and the poles of permanent magnets 202. As tabs 206 rotate betweenthe lower poles of permanent magnets 202 and the upper surface of fluxshunt bar 186, and between the upper poles of the permanent magnets andcore faces 136 of receiver coil 132 (as shown by the dash lines thatillustrate the tabs at those positions in phantom view), the fluxlinkage between permanent magnets 202 and core 134 greatly decreases sothat substantially less magnetic field strength is experienced by thereceiver coil. The magnetic flux produced by the permanent magnets isshunted through disks 204, with little of the magnetic flux flowingbetween the poles of the permanent magnets passing through the receivercoil. However, as disks 204 continue to rotate so that tabs 206 move tothe positions shown by the solid lines in FIG. 10, the flux linkagebetween permanent magnets 202 and receiver coil 132 approaches amaximum. Thus, rotation of disks 204 causes core 134 to experience avarying magnetic field that induces an electrical current to flow withinthe conductor comprising turns 138.

[0072] As shown in FIG. 11, a further embodiment of the varying magneticfield generator includes a fixed flux linkage bar 225 and a rotatingflux linkage shunt 214 connected to a drive shaft 212 that rotates theflux linkage shunt in a plane above the pole faces of permanent magnets202 (as shown in the Figure), so that it passes between the pole facesof the permanent magnets and the pole faces of the receiver coil (notshown here). Fixed flux linkage bar 225 and rotating flux linkage shunt214 are both fabricated of a metal or alloy with high magneticpermeability and thus characterized by its ability to substantiallyshunt magnetic flux. When rotating flux linkage shunt 214 is in theposition represented by the phantom view (dash lines), i.e., in aposition so that its longitudinal axis is oriented about 90° to thelongitudinal axis of fixed flux linkage bar 225, the flux linkagebetween the permanent magnets and the receiver coil is at a maximum, andwhen the rotating flux linkage shunt is in the position shown (by thesolid lines) in FIG. 11, the magnetic flux produced by the permanentmagnets is substantially shunted between them through the rotating fluxlinkage shunt. Due to the resulting periodically varying magnetic fluxcoupled into the receiver coil core, an electrical current is induced inthe receiver coil. FIG. 11 ′ illustrates electrical current pulses 218that are produced in the receiver coil as the flux linkage shuntrotates.

[0073] A desirable feature of the embodiments shown in both FIGS. 10 and11 is that when the devices are de-energized, leaving the magnet fluxshunted between the poles of the permanent magnets, very little magneticfield produced by the permanent magnets escapes outside the housing (notshown) around the flux generator base. The rotating flux linkage shuntsthus serve to “turn off” much of the external magnetic field by shuntingit between the poles of the permanent magnets.

[0074] When the electric motor used as the prime mover for any of theflux generator bases described above is initially energized to providethe rotational, pivotal, or linear reciprocating motion, the motorexperiences a starting torque (that resists its rotation) because of themagnetic attraction between the permanent magnets and any flux linkagebar included in the flux generator base, and the receiver coil. FIG. 12illustrates an embodiment for a flux generator base 230 that minimizesthe starting torque experienced by the electrical motor. In thisembodiment, a drive shaft 232 is coupled to a local or remotely disposedelectrical motor drive 233. The lower end of drive shaft 232 isconnected to a horizontally extending cylindrical tube 236. Permanentmagnets 238 are supported within cylindrical tube 236 and are able tomove radially inward or outward relative to the longitudinal axis ofdrive shaft 232. The permanent magnets are coupled to a helically-coiledspring 234 that extends between the permanent magnets, within the centerof cylindrical tube 236, and applies a force that tends to draw thepermanent magnets radially inward, away from the lower ends of fluxlinkage rods 240 (as shown in the Figure). When the motor drive that iscoupled to drive shaft 232 is de-energized, permanent magnets 238 arethus drawn toward each other, minimizing the torque required to beginrotating cylindrical tube 236. However, after motor drive 233 isrotating drive shaft 232, the centrifugal force created by the rotationof the cylindrical tube overcomes the force of helical spring 234,causing permanent magnets 238 to slide radially outward, away from thecentral axis of drive shaft 232, until the permanent magnets reach stops(not shown) that limit their radial travel, so that their poles areclosely spaced apart from flux linkage rods 240. A varying magnetic fluxlinkage with receiver coil 132 is then achieved.

[0075] In FIGS. 13A and 13B, two alternative techniques are shown forminimizing startup torque. However, a further advantage is provided bythese alternatives, since they enable the magnitude of the currentproduced by the receiver coil to be controlled by varying the spacingbetween permanent magnets 238 and flux linkage rods 240 when thepermanent magnets are rotating past the flux linkage rods. Specifically,as the spacing between the permanent magnets and flux linkage rods isincreased, both the coupling of magnetic flux into the receiver coil andthe magnitude of the electrical current induced in the receiver coil arereduced.

[0076]FIG. 13A shows a flux generator base 248 in which drive shaft 232rotates a ring permanent magnet 250 with a cylindrical tube 236′ andpermanent magnets 238, about the longitudinal axis of the drive shaft. Asolenoid coil 252 is wound around drive shaft 232 and is coupled to anelectrical current source/control 254. Electrical current provided bythe electrical current source/control is varied to provide a controlledmagnetic force that causes ring permanent magnet 250 to move downwardlyalong drive shaft 232 by a controlled amount. Mechanical links 256 arepivotally connected to the ring permanent magnet and extend through aslot 260 in the cylindrical tube to couple with pivot connections 258 onthe facing poles of permanent magnets 238. As the ring permanent magnetis drawn down drive shaft 232, permanent magnets 238 are drawn radiallyinward toward each other, reducing the magnetic flux coupled into thereceiver coil (not shown in this drawing) through flux linkage rods 240.Also, when the drive shaft is initially rotated, the permanent magnetsare drawn relatively closer still to each other, thereby minimizing thestartup torque by reducing the attraction between the permanent magnetsand the flux linkage rods.

[0077] In FIG. 13B, an alternative flux generator base 262 is shown thatachieves much the same result as flux generator base 248. However, inthis embodiment, a swash plate 264 is connected to pivotal connectors258 through mechanical links 256. Swash plate 264, cylindrical tube236′, and permanent magnets 238 are rotated by drive shaft 232. In thisembodiment, bearing rollers 266 act on opposing surfaces of swash plate264 to control its position along drive shaft 232 as the drive shaftrotates. The bearing rollers are mounted on a bracket 268 that isconnected to a piston rod 270.

[0078] The position of the piston rod and thus, the position of thebearing rollers and swash plate, is adjusted by a pressurized fluidcylinder 272 that is actuated by applying pressurized hydraulic orpneumatic fluid through lines 274. The pressurized fluid is applied todrive the piston rod up or down and thereby move swash plate 264 up ordown along drive shaft 232. As the swash plate moves down along driveshaft 232, it pulls permanent magnets 238 radially inward toward eachother. In the fully retracted positions, permanent magnets are onlyweakly linked through flux linkage rods 240, and the startup torquenecessary to begin rotating drive shaft 232 is minimal. As the swashplate is moved upwardly along drive shaft 232, the permanent magnets areforced outwardly, increasing the magnetic flux coupling between therotating permanent magnets and the receiver coil. Accordingly, themagnitude of the electrical current induced in the receiver coil will beincreased. It will be apparent that using either of the embodiments ofthe flux generator base shown in FIGS. 13A or 13B, the magnitude of theelectrical current induced in the receiver coil is readily controlled.

[0079]FIG. 14 illustrates a flux generator base 280 that includes ahousing 282 in which a divider 286 extends between an upper compartment284 and an lower, generally dome-shaped, compartment 288 (as shown inthe Figure). In upper compartment 284 are disposed a motor 290 thatturns a drive shaft 292 at a relatively high speed, e.g., at more than20,000 rpm. Mounted on drive shaft 292 is a rod-shaped permanent magnet294. Motor 290 is energized with an electrical current controlled by amotor speed control circuit 296 that is disposed in lower compartment288. The motor speed control circuit is generally conventional indesign, including, for example, one or more silicon rectifiers or atriac, and is coupled to the motor through a lead 298. The motor speedcontrol circuit is energized with electrical current supplied from aline current energized power supply 304 (or battery pack) to which themotor speed control circuit is connected. A speed control knob 306extends above the housing of the flux generator base and is rotatable bythe user to turn the device on or off and to vary the speed at whichmotor 290 rotates. Speed control knob 306 actuates a variable resistor300, which is mounted just inside the top of the lower compartment,using a pair of threaded nuts 308. The variable resistor is connected tothe motor speed control circuit through leads 302.

[0080] As illustrated in the Figure, flux generator base 280 is intendedto be disposed so that permanent magnet 294 is generally adjacent to anair core receiver coil 276 (or other receiver coil). The term “air core”simply indicates that a ferrous alloy or other material having arelatively high magnetic permeability is not used as a core for thisparticular receiver coil. Instead, this embodiment of a receiver coilcomprises a relatively flat or pancake-shaped coil wound of a conductor.Leads from the air core receiver coil supply electrical current to anappropriate conditioning circuit (not shown). An electrical current isinduced to flow in the coil by the varying magnetic flux produced aspermanent magnet 294 is rotated by the motor. Due to the speed at whichpermanent magnet 294 rotates, a relatively efficient magnetic fluxcoupling exists between the permanent magnet and the air core receivercoil.

[0081] By varying the speed at which the permanent magnet rotates, it ispossible to control the magnitude of the current induced in the air corereceiver coil. As the speed at which the permanent magnet rotates isincreased, the magnitude of the electrical current produced by the aircore receiver coil increases. It is contemplated that speed control knob306 may be indexed to marks (not shown) that are provided on theexterior of housing 282 to indicate a range of electrical current fordifferent settings of the speed control knob. Of course, the magneticflux linkage can also be controlled by varying the separation betweenthe flux generator base and the air core receiver coil.

[0082] Another embodiment of the present invention suitable for use insupplying energy to a portable device is shown in FIGS. 15A and 15B. Theapparatus comprises two primary components, a flux generator base unit310, and a receiving unit 312. The flux generator base unit comprises ahousing 313, a pancake electric motor 314 rotating a shaft 316, and arotor 318. As shown in FIG. 15B, preferably embedded in the rotor (orotherwise attached thereto) are a plurality of magnets 320. The magnetson one side of the rotor are oriented their north pole faces on theupper side of the rotor, while the magnets on the opposite side of therotor have their south pole faces on the upper side of the rotor. Inaddition, the magnets are arranged in pairs such that each paircomprises an upwardly facing north pole on one side and an upwardlyfacing south pole on the opposite side and the magnets on each pair aredisposed at different radiuses from the shaft. The rotor also mayinclude a flux linkage bar 322, that operates in a manner similar tothat of the flux linkage bars described above. It is preferable that thecomponents comprising the flux generator be of low profile, so that theentire device is relatively wide and flat, so that the exterior shape ofthe base unit has the overall appearance of a “tablet.”

[0083] The receiver unit may be either integrated into the portabledevice, or may comprise a separate component that is attached to theportable device. The receiver unit comprises a receiver coil 324, a wirecoil 329, and a conditioning circuit 330 that is connected to the wirecoil via leads 326. It is preferable that the receiver coil and wirecoil be enclosed in a housing 311 (which may be the housing for theportable device). The conditioning circuit may also be included in thereceiver unit housing, or may be separately disposed in the portabledevice. The receiver coil preferable comprises a magnetically permeablecore sized so that the flux lines produced by the flux generator areoptimally coupled with core when the receiver unit is properly alignedwith the flux generator base unit. For example, opposing ends of thecore comprising face portions 325 are disposed parallel to the poles ofthe magnets in the rotor of the flux generator base unit.

[0084] Wire coil 329 is wound around the core member so that when thevariable magnetic field produced by the flux generator is inductivelycoupled into the receiver coil, a current is generated in the wire. Thiscurrent is then rectified, filtered, and regulated by conditioningcircuit 330, which provides a controlled output current at a suitablevoltage for charging a battery 327 and/or energizing electronics 331contained in the portable device. Conditioning circuits of this type arewell known in the art, and may be purchased from various vendors as asingle integrated circuit, such as a model MM1433 integrated circuitdesigned for charging a lithium ion battery made by the MitsumiCorporation of Japan. It will be understood by those skilled in the artthat a different conditioning circuit will be required for other typesof batteries, e.g., a conditioning circuit specifically designed for usewith nickel cadmium batteries will be required when the rechargeablebattery is a nickel cadmium battery.

[0085] Three different size receiver coils 324 are shown in FIG. 15A tomake clear that the flux generator base unit is universally usable withdifferent size portable devices, but it should be clear that a receiverunit for a portable device would typically employ only one receivercoil. The use of three receiver coil core members and three sets ofmagnets shown in the Figure is purely for illustrative purposes. Also, aflux generator in the base unit may comprise only one pair of magnets.If a plurality of pairs of magnets are included, the magnets ofdifferent pairs can be disposed at circumferentially spaced-apartlocations and not just diametrically opposite each other as shown in theFigure.

[0086] To save power and operational wear, it is desirable for the fluxgenerator base unit to operate only when there is a load present (i.e.,a battery to charge or electronics that are energized by the base unit.When a load is not present, the base unit should preferably be in a lowpower consuming “sleep” mode. Therefore, it will be necessary for thebase unit to know when a load is present (so it can “wake up” and begina charging or energy transfer operation) and to know when the battery isfully charged or the load is removed (so the base unit can turn off andgo back to sleep). This behavior can be accomplished in a variety ofways. For example, a Hall-effect sensor 332 (or reed switch) is mountedin the flux generator unit and a magnet 334 is disposed in the center ofthe receiver unit so that the magnet is in close proximity to theHall-effect sensor (or reed switch) when the receiver unit is placed onthe flux generator base unit. The magnetic field produced by magnet 334is sensed by the Hall-effect sensor (or reed switch), causing a changein the output of the sensor. (The change in the output signal of thesensor will depend on whether the sensor includes a normally-open ornormally-closed switch condition). This sensor output signal is coupledthrough a lead 339 to a motor control 341 and enables the motor controlto determine when a load is present so that it can wake up the base unitand energize the motor to produce a current in the receiver coil. Insuch circumstances, the motor will be with a current supplied through alead 345 and the rotor will rotate, causing a variable magnetic field tobe generated. Preferably, the Hall-effect sensor should be positioned inthe center of the rotating magnetic field so that it is notsignificantly affected by it. Correspondingly, the receiver unit magnetshould be disposed relative to the receiver and base units such that thereceiver unit magnet and the Hall-effect sensor are in sufficientlyclose proximity to actuate the sensor only when the flux generator baseunit and receiver unit are properly aligned and mated. It is preferablethat when the Hall-effect sensor output changes state to indicate thatthe receiver unit has been properly positioned on the base unit, anindicator light 337 that is disposed in base unit will be energized withcurrent supplied through a lead 343 by motor control 341. This sameindicator light indicates that the base unit is in an operational mode(i.e., charging a battery). It is also contemplated that anotherindicator light 347 mounted on the receiver unit can be energized by theconditioning circuit when battery 327 in the receiver unit is fullycharged, or conversely, the light can be extinguished when the batteryis fully charged.

[0087] The conditioning circuit controls the current supplied forcharging a battery and determines when the battery is fully charged. Asdiscussed above, several vendors make suitable conditioning circuits forthis purpose. When a battery charging cycle is complete, the energyconsumed by the receiver unit from the flux generator base unit forbattery charging will typically substantially decrease. This conditioncan be sensed in the flux generator by monitoring the current drawn bythe electric motor. When the current is at a reduced level, the batteryhas either been fully charged or has been removed from the fluxgenerator; in either case the flux generator motor can be turned off andgo back to sleep.

[0088] In a more sophisticated feature of the apparatus, the receiverunit can communicate additional information (such as battery conditionor status of the portable device, etc.) to the flux generator base unitfor logging or display, by rapidly switching (i.e., pulsing) the currentsupplied by the conditioning circuit, thereby superimposing “digital”pulses relative to the load experienced by the electric motor in theflux generator base unit, causing corresponding pulses in the motorcurrent due to the pulsed changes in the conditioning circuit load. Theload on the motor will vary as a function of the energy beingtransferred to the receiver unit and consumed by the load, as controlledby the conditioning circuit. A rapid increase in load (even if onlymomentarily) can be “sensed” by a motor controller attempting tomaintain a constant speed as a slowing of the rate at which the magnetsare being rotated, which will require an increase in the motor current.Similarly, a rapid decrease in the load can be sensed by the motorcontroller, which must rapidly decrease the motor current to maintain aconstant speed. The pulse fluctuation in the motor current due to thepulsing of the conditioning circuit load can thus be used to conveydigital data between the receiver unit and the flux generator base unit.This pulse information evident in the motor current can then be decodedto interpret the data information provided from the receiver unit in theportable device, thereby effectively implementing a low-speedcontactless communication channel from the portable device to the baseunit. The information can be displayed at the base unit, or on a display(not shown) separate from the base unit. Optionally, the base unit couldlog the data passed to it from the portable device in an internal memory(not shown).

[0089] It is contemplated that the apparatus shown in FIGS. 15A and 15Bcould be adapted to be used with a variety of different-sized portabledevices. For instance, by using a plurality of magnet pairs placed atdifferent radii, various sized receiver units could be used with asingle “universal” base unit. It is further contemplated that one ofthree or four standard sizes of receiver units might be employed in mostportable devices or used as a separate component relative to theportable device.

[0090] As discussed above, it is also possible to generate a variablemagnetic field by using motions other than a rotary motion. For example,as shown in a flux generator base unit 310′ of FIG. 16, a linear motioncould be applied to a pair of flux generator bars 336, each of whichcomprises a plurality of magnets 338 having north pole faces directedupwardly, and a plurality of magnets 340 with their south pole facesdirected upwardly. As the flux generator bars are moved back and forthin a linear motion, a variable magnetic field is generated relative to afixed magnetic receiver coil (not shown). The receiver coil can be ofvarious sizes, so that its pole faces overlie different sets ofpermanent magnet poles. Although not shown, various well-known drivemechanisms could be used to provide the reciprocating linear motiondriving the flux generator bars.

[0091] Another optional configuration comprising a flux generator baseunit 310″ is shown in FIG. 17, wherein a pair of flux generator bars 342comprising magnets 344 are driven in elliptical path so that the polefaces of the magnets move relative to a fixed receiver coil (not shown),varying the magnetic flux in the receiver coil.

[0092] Further embodiments of universal base units and correspondingreceiving units are shown in FIGS. 18A and 18B, and 19A and 19B. Aprimary feature of the universal base units shown in these Figures isthe step configuration of housings 350 and 350′. (Note that elementshaving reference numbers with a prime notation in FIGS. 19A and 19B aresubstantially similar to the corresponding elements identified by samereference numbers—without a prime—in FIGS. 18A and 18B.) Preferably, thestepped housing is configured so that different sized receiver unit“tablets” 352, 354, and 356 can be easily mated with the base unit.Under this scheme, it is contemplated that the receiver unit tablets areeither separate units, or integrated into the housing of the portabledevices with which they are used. For example, the tablet portion of thereceiving unit could be integrated into the bases of cylindrical batterymodules having various predefined sizes. This design is an alternativeto the various manufacturer-specific battery modules used in differentpower tool lines. In addition, the step configuration of the universalbase units would be suitable for charging the batteries in portabledevices having a cylindrical housing, such as electrically poweredtoothbrushes.

[0093] In order to obtain satisfactory performance using the stephousing, it will be necessary for a rotor similar to rotor 358 to beused. Rotor 358 is generally cylindrical in shape, comprising aplurality of steps at diameters corresponding to the diameters of thesteps in the housing. According to one embodiment, a plurality ofarcuate magnets, similar to those discussed above with reference to FIG.3H, are disposed in sets of opposite polar faces at various diameters,as shown in FIG. 18A. Optionally, wider, low-profile arcuate magnets 362having opposite pole faces directed upwardly on opposite sides of thebase unit could be employed, as shown in FIGS. 19A and 19B. As a furtheroption, a plurality of cylindrical magnets 364 having opposite polefaces directed upwardly on opposite sides of the base unit can be used,as shown in FIG. 19A. Any of these options could be used to generate avarying magnetic flux as rotor 358 is rotated by pancake motor 314.

[0094] The receiver coil in the receiver unit must be sized toinductively couple with the flux generated by one of the sets of magnetsused in the base unit. As was the case with the universal flux generatorbase unit of FIG. 15A, the use of three steps and three differentlysized receiving units is purely illustrative. An actual device couldemploy either fewer or more steps and thus accept either correspondinglysmaller or larger diameter receiving units.

[0095] Although the present invention has been described in connectionwith the preferred form of practicing it, those of ordinary skill in theart will understand that many modifications can be made thereto withinthe scope of the claims that follow. Accordingly, it is not intendedthat the scope of the invention in any way be limited by the abovedescription, but instead be determined entirely by reference to theclaims that follow.

The invention in which an exclusive right is claimed is defined by thefollowing:
 1. A contactless electrical energy transfer apparatuscomprising: (a) a portable receiving unit including: (i) a receivercoil; and (ii) a housing in which the receiver coil is disposed, saidhousing supporting the receiver coil; and (b) a flux generatorincluding: (i) a housing adapted to be disposed proximate to the housingof the receiving unit; (ii) a magnetic field generator comprising atleast one permanent magnet disposed within the housing of the fluxgenerator; and (iii) a prime mover drivingly coupled to an element ofthe magnetic field generator, causing said element of the magnetic fieldgenerator to move relative to the receiver coil, movement of saidelement of the magnetic field generator producing a varying magneticfield that is coupled to the core of the receiver coil, inducing anelectrical current to flow in the receiver coil.
 2. The energy transferapparatus of claim 1 , wherein the receiver coil includes a core formedof a magnetically permeable material.
 3. The energy transfer apparatusof claim 1 , wherein the prime mover is disposed within the housing ofthe flux generator.
 4. The energy transfer apparatus of claim 1 ,wherein the prime mover comprises an electric motor.
 5. The energytransfer apparatus of claim 1 , wherein the prime mover is disposedoutside the housing of the magnetic field generator and is drivinglycoupled to said element of the magnetic field generator through a drivenshaft.
 6. The energy transfer apparatus of claim 1 , wherein said atleast one permanent magnet is mounted on the element that is moved bythe prime mover.
 7. The energy transfer apparatus of claim 1 , whereinsaid at least one permanent magnet comprises a rare earth alloy.
 8. Theenergy transfer apparatus of claim 1 , wherein the magnetic fieldgenerator includes a plurality of permanent magnets and a movablesupport on which the plurality of permanent magnets are mounted, saidprime mover causing the support to move, thereby varying the magneticfield along a path that includes the receiver coil.
 9. The energytransfer apparatus of claim 8 , wherein the support is caused to movereciprocally back and forth in a reciprocating motion.
 10. The energytransfer apparatus of claim 1 , wherein the element of the magneticfield generator that is drivingly coupled to the prime mover comprises amagnetic flux shunt that is moved by the prime mover, to periodicallyshunt a magnetic field produced by said at least one permanent magnet ofthe magnetic field generator, causing the magnetic field to vary along apath that includes the receiver coil.
 11. The energy transfer apparatusof claim 1 , further comprising an adjustment member that is selectivelyactuatable to change a maximum magnetic flux that is coupled to the coreof the receiver coil.
 12. The energy transfer apparatus of claim 11 ,wherein the adjustment member controls a speed with which the element ofthe magnetic field generator is moved.
 13. The energy transfer apparatusof claim 1 , wherein the magnetic field generator includes a pluralityof permanent magnets mounted to the element at radially spaced-apartpoints around a central axis, enabling the varying magnetic fieldproduced by magnetic field generator to couple with a plurality ofdifferent size receiver coils.
 14. The energy transfer apparatus ofclaim 13 , wherein the prime mover rotates the element and the pluralityof permanent magnets about the central axis.
 15. A contactlesselectrical energy transfer apparatus adapted to couple magnetic energyinto a portable device, comprising: (a) a housing having a shapeenabling the contactless electrical energy transfer apparatus to bedisposed proximate a magnetic energy receiving portion of the portabledevice; (b) a prime mover; and (c) a magnetic field generator that isdisposed within the housing, said magnetic field generator comprising apermanent magnet and including an element that is moved by the primemover, causing a varying magnetic field to be produced that is adaptedto transfer energy into the magnetic energy-receiving portion of theportable device.
 16. A contactless electrical energy transfer apparatuscomprising: (a) a portable device including: (i) a receiver coil; and(ii) a housing in which the receiver coil is disposed; and (b) a fluxgenerator including: (i) a housing adapted to be positioned proximate tothe housing for the receiver coil; (ii) a magnetic field generatordisposed within the housing for the flux generator and comprising atleast one permanent magnet and a flux shunt, said at least one permanentmagnet being fixed relative to the receiver coil; and (iii) a primemover that is drivingly coupled to said flux shunt, said flux shuntbeing thereby caused by the prime mover to intermittently pass adjacentto pole faces of said at least one permanent magnet so as to provide amagnetic flux shunt path between the pole faces, thereby varying amagnetic field coupled with the core of the receiver coil to induce anelectrical current to flow in the receiver coil.
 17. The energy transferapparatus of claim 16 , wherein the receiver coil includes a core formedof a magnetically permeable material.
 18. A contactless electricalenergy transfer apparatus adapted to transfer magnetic energy into areceiver coil within a portable device, comprising: (a) a housingadapted to be positioned proximate to a magnetic field receiving portionof the portable device; (b) a magnetic field generator disposed withinthe housing, said magnetic field generator including a permanent magnethaving opposite pole faces, and a flux shunt that is movably mountedwithin the housing; (c) a prime mover that is drivingly coupled to theflux shunt, to cause the flux shunt to move, movement of said flux shuntby the prime mover causing the flux shunt to intermittently passadjacent to the opposite pole faces of said permanent magnet so as toprovide a magnetic flux shunt path between the pole faces, therebyvarying a magnetic field that is coupled with the magnetic fieldreceiving portion of the portable device, to transfer magnetic energy tothe portable device.
 19. The energy transfer apparatus of claim 18 ,wherein the flux shunt comprises a bar of magnetically permeablematerial that includes arms extending over the opposite pole faces ofthe permanent magnet.
 20. The energy transfer apparatus of claim 18 ,wherein the magnetic field generator includes a plurality of permanentmagnets, and a fixed flux linkage bar coupling magnetic flux betweendifferent pole faces of the plurality of permanent magnets, said fluxshunt periodically being moved over opposite pole faces of the pluralityof permanent magnets to produce the varying magnetic field that iscoupled with the magnetic field receiving portion of the portabledevice.
 21. A contactless battery charging/energy transfer apparatuscomprising: (a) a flux generating base unit comprising: (i) an electricmotor having a drive shaft; (ii) a rotor, operatively coupled to thedrive shaft of the electric motor to be rotated thereby and havingattached thereto a plurality of permanent magnets, each permanent magnethaving a north pole face and a south pole face oriented generallyparallel to a rotational plane of the rotor; and (iii) a housing inwhich the electric motor and rotor are disposed, a surface of thehousing defining a contactless mounting interface; (b) a receiving unitthat includes an electrical energy-consuming load and further comprises:(i) a receiver coil having a core formed of a magnetically permeablematerial and an electrically conductive winding around the core; and(ii) a housing in which the receiver coil is disposed and supported, asurface of said housing adjacent to the receiver coil being adapted tobe placed proximate the contactless mounting interface of the housing ofthe flux generator base unit; and (c) a conditioning circuitelectrically connected to the winding of the receiver coil, wherein arotation of the rotor by the electric motor causes the receiver coil toexperience a varying magnetic field, inducing an electrical current toflow in said winding, said electrical current being conditioned by theconditioning circuit for use in supplying electrical energy to the load.22. The contactless battery charging/energy transfer apparatus of claim21 , wherein the load in the receiving unit comprises a rechargeablestorage battery.
 23. The contactless battery charging/energy transferapparatus of claim 21 , wherein the housing of the receiving unit issized and shaped to mate with the contactless mounting interface of theflux generator base unit.
 24. The contactless battery charging/energytransfer apparatus of claim 23 , further comprising a sensor thatproduces a signal indicative of whether the housing of the receivingunit is properly mated with the contactless mounting interface of theflux-generating base unit.
 25. The contactless battery charging/energytransfer apparatus of claim 24 , wherein the sensor comprises one of aHall-effect sensor and a reed switch disposed within the housing of theflux generator base unit, the signal being produced by the sensor inresponse to a magnetic field produced by a permanent magnet disposedwithin the housing of the receiving unit when the housing of thereceiving unit is properly mated with the contactless mounting interfaceof the flux-generating base unit.
 26. The contactless batterycharging/energy transfer apparatus of claim 24 , wherein the electricmotor is energized in response to the signal produced by the sensor, sothat the rotor only rotates when the housing of the receiving unit isproperly mated with the contactless mounting interface of theflux-generating base unit.
 27. The contactless battery charging/energytransfer apparatus of claim 22 , further comprising an indicator thatindicates when the rechargeable storage battery connected to the outputof the conditioning circuit is fully charged.
 28. The contactlessbattery charging/energy transfer apparatus of claim 22 , wherein theconditioning circuit in the receiving unit detects when the batteryconnected to the output of the conditioning circuit is fully charged andreduces the current supplied to the battery upon detecting such acondition.
 29. The contactless battery charging/energy transferapparatus of claim 22 , wherein the flux generator base unit comprises asensor for determining when a battery connected to the output of theconditioning circuit is fully charged, and upon detecting such acondition, causes the electric motor to be de-energized.
 30. Thecontactless battery charging/energy transfer apparatus of claim 21 ,wherein the plurality of permanent magnets are disposed at differentradii from a center of the rotor.
 31. The contactless batterycharging/energy transfer apparatus of claim 21 , wherein a portion ofthe housing of the flux generator base unit adjacent to the rotor isstepped, defining a plurality of contactless mounting interfaceapertures adapted to mate with respective receiving units of varyingsizes corresponding to the sizes of the plurality of contactlessmounting interface apertures.
 32. The contactless batterycharging/energy transfer apparatus of claim 21 , further comprising amotor control that supplies electrical current to the electrical motorand attempts to maintain a rotational speed of the rotor constant, saidmotor control monitoring the current supplied to the electrical motor,wherein a wireless communication channel conveying data is effectedbetween the receiving unit and the flux generator base unit by theconditioning circuit pulsing a load applied to the electrical energyoutput from the conditioning circuit, thereby causing a correspondingpulsing in the electrical current supplied by the motor control to theelectric motor in the flux generator base unit, to supply energy to saidload, said pulsing of the electrical current being detected as a digitalpulse signal conveying the data by the motor control.
 33. A method forcharging a battery by inductively coupling a varying magnetic fieldproduced by a base component to a receiver coil disposed in a receivercomponent, comprising the steps of: (a) positioning the receivercomponent proximate to the base component; (b) generating a magneticfield with a permanent magnet disposed in the base component; (c)coupling a driving force to an element in the base component so that theelement is movable; (d) moving the element with the driving force tovary the magnetic field produced by the permanent magnet, the varyingmagnetic field being inductively coupled to the receiver coil, causing acorresponding electrical current to be induced in the receiver coil; (e)conditioning the electrical current to produce a conditioned current ata voltage suitable for charging a battery; and (f) charging the batterywith the conditioned current.
 34. The method of claim 33 , wherein asource of the driving force is disposed remote from where the magneticfield is generated by the permanent magnet and is coupled to the elementthrough a driven shaft.
 35. The method of claim 33 , wherein themagnetic field is generated by a plurality of permanent magnets.
 36. Themethod of claim 33 , wherein the element that is moved comprises saidpermanent magnet.
 37. The method of claim 36 , wherein the step ofmoving the element comprises the step of rotating the permanent magnetto vary a magnetic flux produced by the permanent magnet along a paththat includes the receiver coil.
 38. The method of claim 36 , whereinthe step of moving the element comprises the step of reciprocating thepermanent magnet back and forth to vary a magnetic flux along a paththat includes the receiver coil.
 39. The method of claim 33 , furthercomprising the step of enhancing a magnetic flux linkage betweenmagnetic poles of the permanent magnet and the receiver coil.
 40. Themethod of claim 39 , wherein the step of enhancing the magnetic fluxlinkage comprises the step of providing a flux linkage bar for couplinga magnetic field from a pole of the permanent magnet into the receivercoil.
 41. The method of claim 33 , further comprising the step ofselectively varying a maximum magnetic field intensity coupled with thereceiver coil.
 42. The method of claim 41 , wherein the step ofselectively varying the maximum magnetic field intensity comprises thestep of varying a position of the permanent magnet relative to thereceiver coil to control the magnetic field coupled to the receivercoil.
 43. The method of claim 41 , wherein the step of selectivelyvarying the maximum magnetic field intensity comprises the step ofchanging a speed with which the element moves.
 44. The method of claim33 , wherein the magnetic field is generated with a plurality ofpermanent magnets.
 45. The method of claim 44 , wherein the movingelement comprises the plurality of permanent magnets, further comprisingthe step of moving one of the permanent magnets, and magneticallycoupling another of the plurality of permanent magnets to the permanentmagnet that is moved, so that the other of the plurality of permanentmagnets is moved thereby.
 46. The method of claim 44 , wherein theplurality of permanent magnets are fixed relative to the base component,and wherein the step of moving the element comprises the step ofintermittently passing a flux shunt member adjacent to pole faces of theplurality of permanent magnets so as to provide a magnetic flux shuntpath between the pole faces of the plurality of permanent magnets, toproduce the varying magnetic field.
 47. The method of claim 44 , whereinthe plurality of permanent magnets are moved laterally back and forthpast the receiver coil to vary the magnetic field.
 48. The method ofclaim 44 , wherein the plurality of permanent magnets are radiallymovable on a support that is rotated to produce the varying magneticfield, further comprising the steps of: (a) forcing the plurality ofpermanent magnets toward each other when the support is at rest toreduce a startup torque required to begin rotating the support; and (b)adjusting a separation between the plurality of permanent magnets whenthe support is rotated, to change a magnitude of the magnetic fieldcoupled to the receiver coil.
 49. The method of claim 41 , wherein thestep of selectively varying the maximum magnetic field intensitycomprises the steps of: (a) providing a plurality of turns of aconductor wound around said permanent magnet; (b) causing an electricalcurrent to flow through the plurality of turns of the conductor toselectively adjust a maximum value of the magnetic field produced bysaid permanent magnet, said electrical current producing a magneticfield that either increases or reduces the magnetic field generated bythe permanent magnet.
 50. The method of claim 41 , wherein said elementis moved sufficiently fast to magnetically couple energy into an aircore receiver coil.
 51. The method of claim 41 , further comprising thestep of providing an indication of whether the receiver component isaligned with the base component.
 52. The method of claim 33 , furthercomprising the step of providing an indication of whether the battery isbeing charged by the conditioned current.
 53. The method of claim 33 ,further comprising the step of providing an indication of whether thebattery is fully charged.
 54. The method of claim 33 , wherein thereceiver component is electrically connected to a portable device. 55.The method of claim 33 , wherein the receiver component comprises aportable device.